Sulfides of aromatic compounds and process of making same



Patented July 1, I930 ROBERT EDER, or ZURICH, swrrzs nrnnn,

. or BASEL, SWITZERLAND INDUSTRY IN BASLE,

AssrGNoR r0. SOCIETY, or CHEMICAL c c sULrIDEs'or ARoMArIccoMPo Nns ANDPROGESS or MAKING sAMr:

in, Drawing. Application filed. May'17, 1928, Serial n5. 278,643, and in SwitzerIand May 27,1927.

The present inventionrelate's to polysulfides of aromatic compounds containing at least one free oresterilied c'arboxylic group,

and it comprises the process of making these compounds, as well as the new compounds themselves.

Hitherto only the mono and disulfides of aromatic carboxylic acids have been known. 7

It is true that Hinsberg (Berichte 1910, vol. 43, page 1874) refers incidentally to a compound Which he regarded as free trithiosalicylicacid'on account of its production b boiling a thioanhydride .ofitrithiosalicylic acid with caustic soda solution of l0per cent strength. However, in viewofthe high degree of instability of the polysulfides, partic; ularlythose of the aromatic carboxylic acids, towards alkalies, it is very unlikely that Hinsberg really produced this acid. t The'present invention isbased on. the observation that: .7 the aromatic ,mercapto-carboxylic acids and their esters of the formula SR l wherein A=aryl, R,=H or its equivalent of a metal, R ,=I-I- or a monovalent hydrocarbon radical, react easily and smoothly with sulfur halides with substitution'offthe hydrogen of the sulfhydryl-groupjby sulfur and union of two carboxylic' acid molecules, the enter; ing sulfurconstituting the connecting bridge, the resulting (A aryl, R. -H' or a'monovalent hydrocar' bon radical, a =a wholenumber higher than two).- 'VVith sulfur halides of the general 40 formula S Hal' trisulfides; are Vproduced,

Halg'tetrasulfides'are produced. v For example; from 25 ercaptobenzoic acid there is" produced by action ofSCl the'dibenzoic acid-2:'2-trisulfide, andby the action of S CI the dibenzoic acid-2 2-tetrasulfid'e cooler COOH Coon C0011 C0011 while with'those of the general formula/S .Sva SH SzC/la S4 products havir'rg" the formula I peutical and technical purposes.

fvention', the parts being by weight ,V

I coolingu The solid 7 'washed with-petroleum ether and dried.

In like manner, when starting fromv an ester ofthe 'mercapto-acid a corresponding dicarboxylic acid-estertrisulfide and dicarboirylic. acid-estertetrasulfide are obtained. These compoundscan'also be obtained from the dicarboxylic 'acid-polysulfides 1 by the usual esterification methods! 1 COOR coon COOR oooH coon y Instead of mercaptobenzoic acid itself a substitution product thereof may bepused,

such'as mercapto-hydroxybenzoic1acid In this manner polysulfides of salicylic acid'and acetyl-salicylic acid may be obtained, for ex'-, ample. I I Thesulfur halides V V are preferably allowed I to act inspresencefof an indifferent organic solvent, such as, ether, chloroform, acetone, methylene chloride or petroleum-ether: 3

Instead of the freemercaptans, metal compounds thereof, suchjas' alkali mercaptides, maybeused.

The free polysulfide fcarboxylic acids may be converted,'in the known manner, by treatment with alcoholic alkalior alkaline earths,

or with alkalialcdholatatoriialkaline earth" alcoholate, into their alkali or alkaline earth salts which are soluble in best to avoid aqueous alkali with care.

"The new compounds are useful for "thera The following exa ples illustrate the in dissolved in a littleether and into th e cooled solution there is droppedgraduallyabout 3.5

parts ,of sulfur dichloride dissolved in'pec I troleum ether. v c separates inlarger partand theseparationis :The trisu lfide thus produced completed by adding 7 matter is filtered and water withwsomef "separation 'of' sulfur 1n th1s reaction it is benzo c acid (melting point 1&644790) are petroleum f ether and l After recrystallization from hot alcohol the dibenzoic acid-3: 3-trisulfide is obtained in the form of green-yellowish crystalline needles of melting point 203 C. It'dissolves very easily in hot methyl alcohol, ethyl alcohol, amyl alcohol or glacial acetic acid. It is somewhat soluble in ether but very slightly soluble in chloroform, benzene or xylene. In sodium carbonate or bicarbonate solution andin ammonia solution it dissolves'first to a clear solution, which quickly becomes turbid V EXAMPLE 2 v Di-benzoz'c Y acid e thyleszier-rf .1 3-po'lysulfides (a). Trisulfida-12 parts of 3-mercaptobenzoic acid-methyl ester (boiling point 137 C. at 11 mm. pressure) are dissolved in about the same volumev of petroleum ether .andthe whole is gradually mixed,.while cooling, with 5 parts of sulfur dichloride dissolved in petroleum ether. The trisulfide separates at first'in the form of an oil which when rubbed in the cold becomes crystalline, forming yellowish-white needles which melt at 3436- C. It is easily soluble inmost organicsolvents,

It dissolves comparatively well in olive oil. Y

. (b). TetrdsuZfideEI-l25 parts of 3-mercaptobenzoic acid-ethylesterare mixed, while cooling, in petroleum ether solution which 6 7 parts of sulfur monochloride dissolved in petroleum ether. The tetrasulfide separates in the form of a yellow oil which is viscous when cold. It has properties of solubility resembling thoseof the trisulfide.

- EzAMPLui Di-salicylio" acid-5 5p0lysulfides (a). Tm'sulfide...25 parts of 5-mercaptosalicylic acid (Soc. 1922, vol. 121, page 2555) are dissolved in dry chloroform and the solution'fis mixed, while cooling with one of 8 parts of sulfur dichloride in chloroform.

Therefseparates immediately a yellow precipitate and to complete the separation there is added an equal volume of petroleum ether. By mixing a'hot alcoholic solution of this product with boiling water the trisulfide is obtained' in the form of beautiful yellow laminae which melt at 224.-225 C. It is soluble inalcohol, ether, ethyl acetate, glacial but somewhat sparingly soluble in petroleum ether.

acetic acid, but very sparingly soluble in chloroform and benzene. In dilute sodium carbonate and bicarbonate solution it dissolves at first clearly but the solution becomes turbid after a short time owing to separation of sulfur. Caustic soda lye decomposes it immediately-l It forms an 'acetyl-derivative which melts at 1% C. V

(b) TetmsuZfida-In analogous manner by substitutingsulfur monochloride :for the sulfur dichloride the disalicylic acid- 5: 5-

tetrasulfide may be made from 5-mercaptsali- 'cylic acid. When recrystallized from ethyl alcohol the compound forms bright yellow lustrous needles, melting at 228 2529" C. i It behaves chemically like the trisulfide, from which, however, it is distinguished by its more I sparing solubility. ,In ether it is. practically insoluble but more freely soluble inhot amyl alcohol. ethyl alcohol, glacial acetic aciduan ethyl acetate.

' EXAMPLE 4 Di-saZicg Zic acid estfi55polysulficles (a). Trisulficla-l0 parts of 5-mercaptosalicylic acid ester (melting point 32 C; boiling point 275 C.) are 'dissolved-inanhydrous ether and the solution is mixed grad ually while coolingwith 2.8 parts of sulfur dichloride. The trisulfide thus obtained is precipitated by addition ofpetroleum ether, while cooling. For purification it is dissolved in ether and the solution is mixed hot with petroleum ether." It forms slender canary yellow needles of melting point 7 7 -7 8 C.

It is freely soluble in most organic solvents but "insoluble in sodium carbonate solution. It is decomposed by caustic soda solution.

The same compound may be obtained by esterifying the disalicylic acid-5 :5trisulfide described in Example 3, for example the trisulfide may be, added to absolute alcohol containing about '20 "per cent I-ICl and the whole boiled in a refluxapparatus for several hours. The ester formed is then precipitated 'bymeans of water, dissolved in ether and shaken with sodium bicarbonate solution to separateYthe' unchanged trisulfide. "After drying and evaporating the ether the ester remains inthe form of a strong yellow crystalline mass which can ,bezpurified asdescribed above. I (b), TetmsuZfide. -In analogous manner by substituting'sulfur. monochloride n-for the sulfur'dichloride, there maybe obtained, according to one or other of the methods de: scribed in a above, the di-salicylic acid-ethyl ester-5:5-tetrasulfide. It forms beautiful pale yellow needles of melti ng point 7 3'741 C. 7 Its chemical b haviour corresponds with that of the .trisulfidebut the, solubility is somewhat greater. v V

The triand tetra'sulfide esters described in Example 2:may also be made by subsequent esterification of the corresponding carboxylic acids described in Example 1, the procedure being analogous to that described inExamp e 4 Analogously to the methods described in the foregoing examples the following triand tetrasulfides can be obtained Trisulfides Melting Properties Di-benzoic Pale yellowish powder sparingly soluble in organic solvents.

08-110 0 Fine white needles, freely soluble in benzene, sparingly Di-benzoic acidethylester-2 :2 -trisulfide.

Pale'greenish yellow crystals,

re-crystalized from petroleum ether benzene.

Yellowish oil, somewhat more Di-benzoic acid-ethylester-4:4-trisulfide.

Di-salicylic acid-allylester-5:5-trisulfide. sparingly soluble than the I et)hyl derivative (Example Di-benzoic aeid-2:2- 296298 O. Yellowish powder, scarcely tetrasulfide. soluble in organic solvents. Di-benzoic acid-431- 293-295" C Yellow crystals scarcely soltetrasulfide. ,uble in organic solvents. Di-salioylic acid-allyl- Yellow oil somewhat more ester-5:5'-tetrasulfide. sparingly soluble than the 23ml derivative (Example What I claim is 1. Process for the treating compounds of the formula wherein A=an aryl radical which may be still further substituted, R=H or its equivalent of a metal, R =H or a mono-Valent hydrocarbon radical, with sulfur halides.

2. Process for, the manufacture of poly sulfides of aromatic compounds containing a chain of more thantwo sulfur atoms by treating compounds of the formula wherein A= an aryl radical which may be still further substituted, R=H or its equivalent of a metal, with sulfur halides.

3.Process for the manufacture of poly sulfides of aromatic compounds containing a chain of more than two sulfur atoms by treating compounds of the formula SR coon wherein A=an aryl radical still further substituted, R=H or its equivasoluble in absolute alcohol.

manufacture of p'olysulfides of aromatic compounds containing a 7 chain of more than two sulfur atoms by the formula wherein A=an aryl radical which may be still further substituted, m= awhole number higher than two, R=H hydrocarbon radical.

6. As new products the-polysulfides of the formula two sulfur atoms by or a monovalent wherein A=an aryl radical which may be" still further substituted, m=a whole number higher than two,R=alkyl.

In witness whereofI have hereunto signed my name this 7th day of May, 1928.

r ROBERT EDER.

which may be 'lent of a metal, with sulfur halides and transforming the free polysulfid carboxylic Q acids thus obtained into their esters. 7

4:. Process for the, manufacture of polyr sulfides of aromatic compounds containing 

